Stairs are arrangements of steps for conveniently ascending and descending from one level to another.
The consideration of iron stairs does not come within the range of these Notes.
The terms common to all stairs will first be mentioned, and also a few general principles universally applicable; after which the construction of stone and wood stairs respectively will be considered more in detail.
The Staircase is the chamber or space which contains the stairs.
This may be a room of the exact size required, the walls of which closely surround and support the steps, as in Fig. 228, or the stairs may be in a large apartment, such as a passage or hall, openings being left in the upper floors so as to allow headway for persons on the steps, and to furnish communication between the stairs and the different stories of the building.
In such a case the stairs are generally, though not necessarily, placed against a wall, as shown in Fig. 194, and the opening is trimmed round in the manner explained at page 91, Part I.
In Factories, or similar large buildings, the staircase should be in a tower projecting from the building, so that it may in case of fire be intact. The best materials for fireproof stairs are, first, wrought iron, then cast iron, then hard wood with plastered soffit. With regard to stone steps, see note, p. 106.
Tread is the horizontal upper surface of the step upon which the foot is placed.
Rise is the vertical height between two treads.
Riser1 is the face or vertical portion of the step.
Nosing is the outer edge of the tread. In most cases it projects beyond the face of the riser and is rounded or ornamented by a moulding, being known, accordingly, as a "rounded" or "moulded" nosing.2 (See Figs. 196, 216.)
Fliers are the ordinary steps of rectangular shape in plan.
Winders 3 are the steps of triangular or taper form in plan, required in turning a corner or going round a curve. The small ends of winders are sometimes called the quoins.
A Curtail Step is described at p. 126.
A Flight is a continued series of steps without a landing.
A Landing 4 is the flat resting-place at the top of any flight.
A Half Space is a landing extending right across the width of the stair.
A Quarter Space is a landing extending half across the width of the staircase.
The Going of a Stair is the horizontal distance from the face of one riser to the face of the next riser, and does not include the nosing or the projection of the tread beyond the face of the riser.
This term is, however, sometimes taken to mean the width of the stair, that is, the length of the steps.
The Going of a Flight is the horizontal distance from the first to the last riser in the flight.
The Line of Nosings is tangent to the nosings of the steps, and thus parallel to the inclination of the stair.
Newels are posts or columns used in some kinds of stairs to receive the outer ends of steps. (See Figs. 223, 224.) The name "newel" is sometimes applied to the final baluster on a curtail step.
When the newels surround a central opening, as in Fig. 226, the staircase is said to have an " open newel."
The Handrail is a rounded or moulded rail, parallel nearly throughout its length to the general inclination of the stair, and at such a height from the steps as to be conveniently grasped by a person on the stairs.
Balusters are slight posts or bars supporting the handrail.
The dimensions of staircases and steps are regulated by the purposes for which they are intended.
Sometimes spiral staircases are constructed in very cramped positions, with steps only 1 foot 9 inches long; but, as a rule, steps should not be less than from 3 to 4 feet long, so as to allow two people to pass, and in superior buildings they are very much longer.
1 Sc. Breast. 2 Sc. Bottled or Bottle-nosed step. 3 Sc. IVheeling steps. 4 Sc. Plat.
The stairs in the illustrations given with these Notes are necessarily shown narrow for want of space.
The wider .the step the less the rise should be, as steps which are both wide and high require a great exertion to climb.
Authorities differ slightly as to the proportion between the tread and riser; the following table is given by Mr. Mayer in Newland's Carpenter's and Joiner's Assistant.
The following rule is often adopted for steps of the dimensions ordinarily required in practice, i.e. those with treads from 9 inches to 14 inches wide: -
Width of tread x height of riser = 66 inches.
Thus with a tread of 12 inches riser would be 5½ inches ; with a riser of 6 inches the tread would be 11 inches.
The rule adopted in France, where they have given great attention to the subject, is as follows: - "Inasmuch as on the average human beings move horizontally 2 feet in a stride, and as the labour of rising vertically is twice that of moving horizontally, the width of the tread added to twice the height of the rise should be equal to 2 feet."
The proportion that the tread and riser bear to one another cannot always in practice be fixed by rule, but is regulated by the space - as regards both plan and height - that can be afforded for the staircase.
The tread of a step should, however, never be less than 9 inches in width, even for the commonest stair; while, for first-class houses and public buildings, the stairs may have treads from 12 to 14 inches wide.
Flights should, when possible, consist of not more than 12 or 13 steps, after which there should be a landing, so that weak people may have a rest at short intervals.
Two consecutive flights ought not to be in the same direction (see p. 130).